Method and device for operating an internal combustion engine of a motor vehicle

Abstract

To operate an internal combustion engine of a motor vehicle, during a plurality of driving cycles of the motor vehicle at least one operating variable is recorded during each run which is representative of a harmful substance content of an exhaust gas of the internal combustion engine. The recorded runs are analyzed with respect to recurring run patterns. In a current driving cycle of the motor vehicle, a target value of an ammonia charge level of an exhaust gas catalyst of the internal combustion engine is determined using the recurring run pattern, depending on which, at least one actuating signal for an actuator is determined, the position of which affects an actual ammonia charge level of the exhaust gas catalyst. In order to convert the determined target value of the ammonia charge level of the exhaust gas catalyst, the actuator is controlled as a function of the actuating signal.

1 . A method of operating an internal combustion engine of a motor vehicle, comprising the steps of:
 during a plurality of driving cycles of the motor vehicle:   
       logging, in each case, one run of at least one operating variable of the internal combustion engine that is representative of a noxious substance content of an exhaust gas of the internal combustion engine is logged, 
       analyzing the logged runs with regard to recurring run patters, and
 during an actual driving cycle of the motor vehicle: 
 
       determining a setpoint value of a degree of ammonia loading of an exhaust gas catalytic converter of the internal combustion engine by using the recurring run patterns, 
       depending upon the determined setpoint value of the degree of ammonia loading, determining at least one actuating signal for an actuator, the position of which affects an actual degree of ammonia loading of the exhaust gas catalytic converter, and 
       to convert the determined setpoint value of the degree of ammonia loading of the exhaust gas catalytic converter, controlling the actuator depending upon the actuating signal. 
     
     
         2 . The method according to  claim 1 , wherein the recurring run patterns are used during determination of the setpoint value of the degree of ammonia loading only if a frequency, with which the corresponding recurring run patterns occur in each case in the logged runs, is greater than a preset threshold value. 
     
     
         3 . The method according to  claim 1 , wherein during the actual driving cycle of the motor vehicle the setpoint value of the degree of ammonia loading of the exhaust gas catalytic converter is determined using the recurring run patterns in that
 an actual run of the operating variable is determined,   using the recurring run patterns and depending upon the determined actual run of the operating variable a trend, with which the noxious substance content of the exhaust gas is expected to vary, is determined,   depending upon the determined trend the setpoint value of the degree of ammonia loading of the exhaust gas catalytic converter is determined and converted.   
     
     
         4 . The method according to  claim 3 , wherein the setpoint value of the degree of ammonia loading of the exhaust gas catalytic converter is determined and converted in such a way that after conversion of the setpoint value of the degree of ammonia loading of the exhaust gas catalytic converter the exhaust gas catalytic converter is loaded in such a way with ammonia that the nitrous oxides then contained in the exhaust gas may be transformed with the ammonia. 
     
     
         5 . The method according to  claim 3 , wherein the trend is evaluated with a probability value that is representative of the probability that an actual run of the noxious substance content of the exhaust gas will follow the determined trend, and wherein the setpoint value of the degree of ammonia loading of the exhaust gas catalytic converter is determined depending upon the determined trend only if the probability value is greater than a preset second threshold value. 
     
     
         6 . An apparatus for operating an internal combustion engine of a motor vehicle, which is operable
 during a plurality of driving cycles of the motor vehicle:   
       to log in each case one run of at least one operating variable of the internal combustion engine that is representative of a noxious substance content of an exhaust gas of the internal combustion engine, 
       to analyze the logged runs with regard to recurring run patterns, and
 during an actual driving cycle of the motor vehicle: 
 
       to determine a setpoint value of a degree of ammonia loading of an exhaust gas catalytic converter of the internal combustion engine by using the recurring run patterns, 
       depending upon the determined setpoint value of the degree of ammonia loading, to determine at least one actuating signal for an actuator, the position of which affects an actual degree of ammonia loading of the exhaust gas catalytic converter, and 
       to control the actuator depending upon the actuating signal in order to convert the determined setpoint value of the degree of ammonia loading of the exhaust gas catalytic converter. 
     
     
         7 . The apparatus according to  claim 6 , wherein the apparatus is operable to use the recurring run patterns during determination of the setpoint value of the degree of ammonia loading only if a frequency, with which the corresponding recurring run patterns occur in each case in the logged runs, is greater than a preset threshold value. 
     
     
         8 . The apparatus according to  claim 6 , wherein the apparatus is operable to determine, during the actual driving cycle of the motor vehicle, the setpoint value of the degree of ammonia loading of the exhaust gas catalytic converter using the recurring run patterns in that
 an actual run of the operating variable is determined,   using the recurring run patterns and depending upon the determined actual run of the operating variable a trend, with which the noxious substance content of the exhaust gas is expected to vary, is determined,   depending upon the determined trend the setpoint value of the degree of ammonia loading of the exhaust gas catalytic converter is determined and converted.   
     
     
         9 . The apparatus according to  claim 8 , wherein the apparatus is operable to determine the setpoint value of the degree of ammonia loading of the exhaust gas catalytic converter and to convert the setpoint value in such a way that after conversion of the setpoint value of the degree of ammonia loading of the exhaust gas catalytic converter the exhaust gas catalytic converter is loaded in such a way with ammonia that the nitrous oxides then contained in the exhaust gas may be transformed with the ammonia. 
     
     
         10 . The apparatus according to  claim 8 , wherein the apparatus is operable to evaluate the trend with a probability value that is representative of the probability that an actual run of the noxious substance content of the exhaust gas will follow the determined trend, and wherein the setpoint value of the degree of ammonia loading of the exhaust gas catalytic converter is determined depending upon the determined trend only if the probability value is greater than a preset second threshold value. 
     
     
         11 . An motor vehicle comprising an internal combustion engine and an apparatus which is operable:
 during a plurality of driving cycles of the motor vehicle:   
       to log in each case one run of at least one operating variable of the internal combustion engine that is representative of a noxious substance content of an exhaust gas of the internal combustion engine, 
       to analyze the logged runs with regard to recurring run patterns, and
 during an actual driving cycle of the motor vehicle: 
 
       to determine a setpoint value of a degree of ammonia loading of an exhaust gas catalytic converter of the internal combustion engine by using the recurring run patterns, 
       depending upon the determined setpoint value of the degree of ammonia loading, to determine at least one actuating signal for an actuator, the position of which affects an actual degree of ammonia loading of the exhaust gas catalytic converter, and 
       to control the actuator depending upon the actuating signal in order to convert the determined setpoint value of the degree of ammonia loading of the exhaust gas catalytic converter. 
     
     
         12 . The motor vehicle according to  claim 11 , wherein the apparatus is operable to use the recurring run patterns during determination of the setpoint value of the degree of ammonia loading only if a frequency, with which the corresponding recurring run patterns occur in each case in the logged runs, is greater than a preset threshold value. 
     
     
         13 . The motor vehicle according to  claim 11 , wherein the apparatus is operable to determine, during the actual driving cycle of the motor vehicle, the setpoint value of the degree of ammonia loading of the exhaust gas catalytic converter using the recurring run patterns in that
 an actual run of the operating variable is determined,   using the recurring run patterns and depending upon the determined actual run of the operating variable a trend, with which the noxious substance content of the exhaust gas is expected to vary, is determined,   depending upon the determined trend the setpoint value of the degree of ammonia loading of the exhaust gas catalytic converter is determined and converted.   
     
     
         14 . The motor vehicle according to  claim 13 , wherein the apparatus is operable to determine the setpoint value of the degree of ammonia loading of the exhaust gas catalytic converter and to convert the setpoint value in such a way that after conversion of the setpoint value of the degree of ammonia loading of the exhaust gas catalytic converter the exhaust gas catalytic converter is loaded in such a way with ammonia that the nitrous oxides then contained in the exhaust gas may be transformed with the ammonia. 
     
     
         15 . The motor vehicle according to  claim 13 , wherein the apparatus is operable to evaluate the trend with a probability value that is representative of the probability that an actual run of the noxious substance content of the exhaust gas will follow the determined trend, and wherein the setpoint value of the degree of ammonia loading of the exhaust gas catalytic converter is determined depending upon the determined trend only if the probability value is greater than a preset second threshold value. 
     
     
         16 . The motor vehicle according to  claim 11 , further comprising an exhaust gas after-treatment system associated with an exhaust gas tract . 
     
     
         17 . The motor vehicle according to  claim 16 , wherein the exhaust gas after-treatment system comprises a reducing agent tank for receiving a reducing agent comprising said ammonia, a reducing agent metering valve and a reducing agent pump for supplying reducing agent from the reducing agent tank to the reducing agent metering valve. 
     
     
         18 . The motor vehicle according to  claim 17 , wherein the reducing agent tank preferably comprises a urea tank  40 , the reducing agent metering valve comprises a urea injection valve. 
     
     
         19 . The motor vehicle according to  claim 17 , wherein the reducing agent further comprises a complex salt.  6757109   
     
     
         20 . The motor vehicle according to  claim 17 , wherein upstream of the urea injection valve a particulate filter is disposed and downstream of the urea injection valve a mixing apparatus is disposed for mixing the metered urea with exhaust gas in the exhaust gas tract.